Some of the industrial vehicles such as a forklift and a shovel loader include diesel engines as power sources. Incidentally, emissions control is applied to diesel engine vehicles, and it is obligatory to reduce hazardous substances in exhaust gas, such as particulate matter (PM), sulfur oxide, and nitrogen oxide (NOX), to standard values or lower. Accordingly, industrial vehicles equipped with diesel engines also have exhaust gas purification devices attached on the upstream side relative to exhaust pipe mufflers of the engines.
For example, conventional forklifts equipped with diesel engines have work devices provided at the front of bodies, and also have counterweight portions provided at the rear of the bodies in order to balance loads on the work devices, and the engines are attached to the bodies and positioned forward from the counterweight portions (see, for example, Patent Documents 1 and 2). Moreover, provided in the counterweight portions are ventilation paths extending in the front-rear direction of the bodies.
Furthermore, there are radiators disposed rearward from the engines so as to be positioned immediately before front end openings of the ventilation paths or at the front of the ventilation paths, and also disposed between the engines and the radiators are radiator fans for cooling the radiators. Accordingly, airflows generated by rotation of the radiator fans are exhausted through the ventilation paths to the outside of the bodies.
Further, the forklifts include exhaust pipes, exhaust gas purification devices and mufflers, in which the exhaust pipes are supported by the bodies, connected to the engines at one end, and protrude from the rear of the bodies to the outside at the other end, and the exhaust gas purification devices and the mufflers are provided at some positions along the exhaust pipes. Typically, the exhaust gas purification device and the muffler have a cylindrical outer shape, and constitute a relatively large component unit in the forklift in the case where the forklift is small.
Still further, the operating temperature of the exhaust gas purification device is considerably high (about 400 to 800° C.), and in addition, the exhaust gas purification device is designed to be heated by exhaust gas and therefore is preferably disposed as close as possible to an exhaust manifold of the engine.
Accordingly, there is an issue as to where in the body to dispose an engine exhaust system, which consists of the exhaust pipe, the exhaust gas purification device, and the muffler, and in this case, for reasons concerned with the structure of the forklift, it is desirable to not change the existing arrangement of the engine, the radiator, the radiator fan, and the counterweight portion on the body (i.e., the positional relationship therebetween).
Therefore, in the conventional art, considering the downsizing of the body, the ensuring of the driver's view, prevention of burns to the driver, easy maintenance of the exhaust gas purification device, etc., the engine exhaust system is accommodated in the counterweight portion, and further, the exhaust gas purification device is disposed so as to face the back of the radiator (see, for example, Patent Documents 1 and 2).
However, although this configuration allows the exhaust gas purification device to be cooled by cooling air directly blowing from the radiator fan that is rotating, the radiator is heated by being subjected to radiation heat straight from the exhaust gas purification device, resulting in an issue of compromising both the efficiency of cooling an engine coolant by the radiator and the efficiency of purifying exhaust gas by the exhaust gas purification device.